Enlarge / Wildfire smoke hovers over the Pacific coast of northern New South Wales, Australia in September 2019. (credit: Orbital Horizon/Copernicus Sentinel Data/Gallo Images via Getty Images)

The aerosol fallout from wildfires that burned across more than 70,000 square miles of Australia in 2019 and 2020 was so persistent and widespread that it brightened a vast area of clouds above the subtropical Pacific Ocean.

Beneath those clouds, the ocean surface and the atmosphere cooled, shifting a key tropical rainfall belt northward and nudging the Equatorial Pacific toward an unexpected and long-lasting cool phase of the La Niña-El Niño cycle, according to research published today in Science Advances.

Aerosols from wildfires are basically fire dust—microscopic bits of charred mineral or organic matter that can ride super-heated wildfire clouds up to the stratosphere and spread across hemispheres with varied climatic effects, depending on where they’re produced and where they end up.

To call what’s happening in the oceans right now an anomaly is a bit of an understatement. Since March, average sea surface temperatures have been climbing to record highs , as shown in the dark line in the graph below.

(credit: Sean Birkel/University of Maine)

Since this record-keeping began in the early 1980s—the other squiggly lines are previous years—the global average for the world’s ocean surfaces has oscillated seasonally between 19.7° and 21° Celsius (67.5° and 69.8° Fahrenheit). Toward the end of March, the average shot above the 21° mark and stayed there for a month. (The most recent reading, for April 26, was just a hair under 21°.) This temperature spike is not just unprecedented, but extreme.

“It’s surprising to me that we’re this far off the trajectory,” says Robert Rohde, lead scientist at Berkeley Earth, a nonprofit that gathers climate data. “Usually when you have a particular warming event, we’re beating the previous record by a little bit. Right now we’re sitting well above the past records for this time of year, for a considerable period of time.”

Enlarge (credit: James Wakibia/Getty Images)

the middle of its worst drought in 40 years . In the parched north of the country, rivers are running dry and millions of livestock have perished due to lack of food. Around 4.4 million Kenyans don’t have enough to eat, and the situation will worsen if the coming rainy season fails like the previous five. “I’ve never seen it so bad. There’s nothing in the farms, the drought is too harsh,” says Daniel Magondo, a cotton and maize farmer in central Kenya.

The record-breaking drought is forcing Kenya to confront a controversial topic: whether the country should grow genetically modified (GM) crops. These are plants that have had genes from another organism inserted into their DNA to give them a new trait, such as disease or drought resistance. Although GM crops are completely safe to eat and are widely grown in the US, Canada, Brazil, and India, governments in many parts of the world, including Europe and East Africa, have pushed back against them.

Enlarge / A warming climate can lead to more extreme downpours, as Bangladesh and India experienced in 2022 (credit: https://www.gettyimages.com/detail/news-photo/people-try-to-survive-as-monsoon-rains-swamped-huge-areas-news-photo/1241419969 )

There’s an old joke about the fellow who has his left foot in a bucket of ice water and the right in a bucket of hot water, so that his overall temperature is average. That seems to apply to the climate during 2022’s northern summer of extremes : Overall, the planet was tied for only the fifth-warmest June-August , yet regional heat waves shattered records.

Global warming is undoubtedly a factor, but just how the increasing extremes that marked the summer of 2022—heat waves, droughts and floods, sometimes one on top of the other—are related can be bewildering to the public and policymakers.

As a climate scientist , I’ve been working on these issues for more than four decades, and my new book, “ The Changing Flow of Energy Through the Climate System ,” details the causes, feedbacks, and impacts. Let’s take a closer look at how climate change and natural weather patterns like La Niña influence what we’re seeing around the world today.